The present invention relates to a magnetic disk which achieves high recording density.
FIG. 1 shows an arrangement of a conventional magnetic disk.
An aluminum substrate 2 is used as a substrate of a magnetic disk 1. A texture 3 is formed on the entire surface of the aluminum substrate 2. Films such as a magnetic recording film are formed on the texture 3. A lubricant 4 is coated on the entire surface of the magnetic recording film. Reference numeral 5 denotes an opening formed in a central portion of the aluminum substrate 2.
The texture 3 is formed because the texture 3 serving as a surface structure of the aluminum substrate 2 has a significant influence on "contact start stop" characteristics between the magnetic disk 1 and a magnetic head (not shown) and electromagnetic conversion characteristics.
For example, only a very small gap is formed between the magnetic disk 1 and the magnetic head. Therefore, when the magnetic disk 1 and the magnetic head are stopped relative to each other, they are substantially in contact with each other. When the magnetic disk 1 is rotated and driven, they tend to stick each other. However, this sticking state must be reliably released. For this reason, the texture 3 is formed on the aluminum substrate 2 in conventional techniques.
In such a conventional magnetic disk 1, however, the texture 3 is formed, and smoothness of the aluminum substrate 2 is low. Therefore, considerable waviness is present on a surface of the aluminum substrate 2. For this reason, during an operation of the magnetic disk apparatus, a gap formed between the magnetic disk 1 and the magnetic head cannot be set to be smaller. In other words, in the conventional aluminum substrate 2, a floating amount of the magnetic head cannot be decreased. As a result, recording density cannot be increased.
In addition, a lubricant is coated on the entire surface of a data surface of the magnetic disk 1. For this reason, dust tends to attach to the data surface.